Paclitaxel has been approved as one of the most important anticancer drugs over the last 15 years. Natural products (e.g., paclitaxel), called “taxanes”, are known as therapeutic drugs for cancer-associated diseases, and their applications have been expanded to many other drugs. Paclitaxel is a natural taxane extracted from the bark of the Pacific yew tree (Taxus Brevifolia). In addition, taxanes are derived from Taxus baccata, Taxus canadensis, Taxus wallichiana, Taxus yunnanensis, Taxus densiformis, Taxus hicksii, Taxus wardii, Taxus cuspidata, Taxus capitata, Taxus brownie, etc. [Miller et al. J. Org. Chem., 46: 1469 (1981); McLaughlin et al. J. Nat. Prod., 44: 321 (1981); Kingston et al. J. Nat. Prod., 45: 466 (1982)].
Taxanes are also derived from in-vitro cultured plant cells (U.S. Pat. Nos. 5,019,504; 5,637,484; 5,665,576; 5,871,979), fungi (U.S. Pat. No. 5,322,779), bacteria (U.S. Pat. No. 5,561,055), etc.
Taxanes, i.e., crude taxane extracts were tested for drug screening in 1960. An effective ingredient (paclitaxel) of a crude taxane extract was separated by Wani et al. in 1971, and the chemical structure of paclitaxel was identified by the same group. Paclitaxel has a potent, broad-spectrum anticancer activity in animal models of solid tumors, melanoma, leukemia, various cancers, sarcomas, and non-Hodgkin lymphomas. Clinical trials using paclitaxel have demonstrated that paclitaxel-containing drugs have potent cancer-combating properties. Thus, paclitaxel (Taxol™) and its semisynthetic analogue, docetaxel (Taxotere™) have been used alone or in combination with other drug(s), such as cisplatin, for the treatment of ovarian cancer, breast cancer, and non-small-cell lung cancer.
The analysis of paclitaxel and other taxanes is performed mainly by reverse-phase High-Performance Liquid Chromatography (reverse-phase HPLC), although other methods such as multimodal thin layer chromatography, micellar electrokinetic chromatography, tandem mass spectrometry, and gas chromatography have been reported. Reverse-phase HPLC is more effective in yielding taxane crystals, and the HPLC-based separation of taxanes from both plant materials and biological fluids was recently reported by Theodoridis, et al. [Phytochem. Anal. 7: 169-184, 1996]. In order to effectively separate taxane from a taxane mixture, there has been used an HPLC column packed with silica, alumina, an alkyl (e.g., C18 and C8)—functionalized silica resin, or a polystyrene divinylbenzene resin. For the purpose of appropriate separation of taxanes, researchers have developed silica gels modified with a diversely functionalized alkyl chain, such as a phenyl-, biphenyl-, pentafluorophenyl-, or cyano-modified silica gel. Ketchum, et al. [J. Liq. Chromatogr. 16: 2519-2530, 1993] investigated a separation efficiency of taxanes according to the type of a stationary phase column. Furthermore, a polyfluorinated reverse-phase column for taxane separation was recently reported [Anal. Chim. Acta., 319: 187-190, 1996]. As a result of intensive research on a column material, some companies have developed various silica-based columns, such as Phenomenex, Curosil, Whatman TAC1, Metachem Taxil, and Zorbax SW-Taxane. However, some of these columns are more suitable for bark extracts, and some other columns are more suitable for needle extracts. More recently, a polymer-coated silica material for taxane separation was developed (PCT International Publication No. WO 2004/083176).
However, the above-described techniques have some limitations in terms of purification costs and product purity. Therefore, a taxane purification technique capable of reducing purification costs and increasing taxane purity is needed.